During the process of burning coal in utility or large industrial furnaces, fly ash particles are produced. These fly ash particles constitute about 10% of the total weight of the coal burned and fly ash historically was considered a waste product which was collected and shipped to designated land fill sites for disposal. Depending upon the particular type of coal which was burned, the fly ash particles could contain mineral content which made disposal difficult and expensive.
As disclosed in U.S. Pat. Nos. 5,160,539 and 5,399,194, which are each herein incorporated by reference in their entirety, techniques to utilize these fly ash particles for a beneficial purpose have been developed. More specifically, these patents disclose systems and methods for using combustion processes to thermally beneficiate fly ash particles by reducing the carbon content. The fly ash particles beneficiated by these inventions can be used as a substitute for a portion of Portland cement.
Unfortunately, prior to the development of the above-identified techniques, substantial amounts of fly ash particles had already been disposed of in designated landfill sites. Additionally, despite these breakthroughs substantial amounts of fly ash particles from coal burning plants that do not utilize this technology continue to be disposed of in designated landfill sites. Unfortunately, the high moisture content of landfill fly ash gives it physical properties that make it unusable as a feed material for the above-identified techniques as well as for other competing fly ash beneficiation techniques. To date, no commercially viable techniques to reclaim and beneficiate the fly ash particles which have been disposed of in these landfills have been developed.